NEW YORK (CNN/Money) - Blue-chip stocks rose for the sixth straight session Wednesday as U.S. troops advanced on Iraq, but what happens to the market once the war starts is anyone's guess on Wall Street.

"I think the initial reaction when the ground war starts is going to be a little pop up, but then you're going to see some pullback, regardless of how it progresses," said John Hughes, a market analyst at Shields & Co. "After the runup we've seen in the last week, we might have seen a pullback anyway, but people are going to use the war as an excuse to sell."

The basic issue: Wall Street has been betting the war will be short and go well for the United States.

That sentiment again boosted stocks Wednesday, with the Dow Jones industrial average (up 71.22 to 8265.45, Charts) rising 0.9 percent for its sixth straight gain, its longest winning streak since August 2000. The world's most widely watched stock index has risen 9.8 percent over that span.

The S&P 500 index (up 7.57 to 874.02, Charts) also rose 0.9 percent, while the Nasdaq composite (down 3.48 to 1397.07, Charts) ended down 0.3 percent. All three indexes had traded on both sides of unchanged throughout the session.

Wednesday night brings the expiration of the 48-hour deadline President Bush set for Iraqi President Saddam Hussein to quit the country with his family. Hussein has rejected the ultimatum.

Meanwhile, coalition warplanes struck Iraqi artillery sites, a military convoy headed toward Iraq, and a small group of Iraqi troops surrendered to U.S. forces. The air strikes gave a late-session lift to stocks. (For the latest coverage on the conflict with Iraq, go to CNN.com.)

"That implies that the war should be short," said Brian Finnerty, managing director at Melhado Flynn & Associates, referring to the surrender. "But I'm sure there are all kinds of booby traps the Iraqi regime is planning for us that we can't anticipate so there's still a great deal of nervousness."

What impact a war would have on the markets, even in the short run, is unclear. In the session after the start of the Gulf War, in January 1991, crude oil tumbled, Treasury bonds rallied, pushing the 10-year Treasury yield down to 8.05 percent, and the Dow jumped 4.5 percent.

In other markets Wednesday, Treasury bonds, oil and gold all sank again. The dollar rallied.

Stocks largely repeated their Tuesday performance, criss-crossing in and out of positive territory in a tight range before turning mostly higher late in the session. Traders still believe the war is likely to be short and that once it's over, corporations will be willing to spend again, giving a lift to the economy.

But that was not the view at the Federal Reserve Tuesday. The central bank left interest rates unchanged but also declined to offer any outlook for the economy, citing the uncertainty created by a world on the edge of war. The Fed did share its disappointment with the condition of the U.S. labor market.

Some analysts said that once the issue of war is past, investors will be forced to acknowledge the same problems that hurt stocks for months before the recent rally: sluggish economic growth, weak corporate profit growth, and a huge slump in the tech and telecom sectors.

Thursday will bring reports on weekly jobless claims, expected to show a modest decline from the previous week, and leading indicators for February, forecast to show a small drop from January.

In addition, earnings are due from Goldman Sachs (GS: Research, Estimates), Lehman Brothers (LEH: Research, Estimates), Morgan Stanley (MWD: Research, Estimates), and Micron Technology (MU: Research, Estimates).

Among active issues Wednesday, Dow component Altria Group (MO: up $1.21 to $33.81, Research, Estimates), parent of Phillip Morris, rose nearly 4 percent along with other tobacco stocks after Morgan Stanley issued a bullish note on the sector. The firm raised its rating on the industry to "attractive" from "in-line," saying it believes investors are pricing a "worst-worst" case scenario into the stock regarding litigation and earnings, one Morgan Stanley believes is unlikely to unfold.

Two other Dow components, Merck (MRK: up $1.44 to $54.46, Research, Estimates) and Home Depot (HD: up $0.61 to $24.55, Research, Estimates), each gained more than 2.5 percent.

Shares of online discount travel site Priceline.com (PCLN: up $0.46 to $1.93, Research, Estimates) jumped in active trading after the company said late Tuesday that it had bought a stake in Travelweb, an online lodging company, for about $8.5 million. Travelweb will replace hotel supplier Hotels.com (ROOM: up $1.43 to $54.67, Research, Estimates) at Priceline.com's lowestfare.com affiliate.

Expedia (EXPE: up $8.23 to $47.13, Research, Estimates) gained 21 percent after USA Interactive said it will buy the remaining stake of the online travel booker it doesn't already own for $3.3 billion in stock.

On the downside, Oracle (ORCL: down $0.94 to $11.31, Research, Estimates) tumbled after issuing a weak sales forecast late Tuesday, on top of disappointing licensing revenue for its fiscal third quarter. Semiconductor maker Microchip Technology (MCHP: down $2.24 to $21.50, Research, Estimates) fell 9 percent and was one of the Nasdaq's most active issues after the firm lowered its guidance late Tuesday, due to weaker-than-expected sales.

Market breadth was positive, with winners edging losers on the New York Stock Exchange and the Nasdaq market. On the NYSE, 1.42 billion shares changed hands, while on the Nasdaq, 1.68 billion shares traded.

U.S. Treasury bonds continued to see a rise in yields. The 10-year note lost 12/32 of a point in price, pushing its yield up to 3.97 percent. The dollar rallied against both the euro and the yen.

The price of oil fell, with light sweet crude losing 60 cents to $29.45 a barrel in New York. Gold fell $1.50 to $336.20 an ounce in New York.